I. Field of the Invention
The present invention relates to sound suppression elements or means for reduction, abatement, or suppression of annoying and harmful noise produced by crowds of people, traffic on roads, highways, and freeways, industrial machinery, or by jet aircraft during takeoff and runup at airports. The instant invention pertains to a new and improved means for noise suppression and abatement with universal application.
II. Description of Related Art
In order to properly describe the prior art related to the present invention one must look to all of the possibilities of application of the present invention. Since the present invention has a broad application, the following areas of application are considered: buildings where people congregate, and especially larger buildings such as auditoriums and sports arenas; highways and freeways; industrial applications; and airports.
In large buildings such as gymnasiums, auditoriums, sports arenas, and theatres sound suppression is often attempted with ceilings of fiberglass squares and walls that are carpeted or designed with irregular surfaces. Conventional methods absorb some of the noise, but reflect a high percentage back to the crowd or transmit the excess noise to the exterior of the building.
Suppression of freeway or highway traffic noise in populated areas is either forgotten or interrupted by growing trees and bushes along the freeways, an approach that is of limited value. Another approach is to use masonry walls along the freeways to reflect the traffic noise upwardly and away. The fault in this approach is that the noise then becomes a major annoyance for neighborhoods that are some distance from the traffic.
The noise which can be annoying, and hazardous from industrial machinery has seldom been treated. If the machinery was indoors only the building and possibly machinery housings were used to shield the sound. However, this did not effectively suppress the sound nor did it protect employees or operators.
The methods employed for suppression of noise produced by jet aircraft during jet engine runup and takeoff vary based upon the containment of the airplane. Jet engines are commonly run up to full power while on the ground to test the engines. This results in a great amount of noise and a tremendous blast of hot exhaust gases from the engines of the aircraft. The term commonly used for this activity is "engine runup". On takeoff the blast is ordinarily directed upward by blast fences that are constructed at the ends of airport runways. The blast fences reflect the gases exhausted by the jet engines, but the blast fences have very little effect upon the noise created that can be heard for miles.
During engine runup and testing, the airplanes can be contained at one location. The usual methods of sound suppression during runup and testing include containment in a ground runup enclosure (GRE). GRE's usually consist of a fence that surrounds the airplaine on at least three (3) sides. The blast from the engine is deflected by a blast fence that is placed at some distance behind the jet engines. Behind the blast fence would be disposed a wall that is considerably taller than the blast fence. The wall supports a matrix of boxes which are attached side to side and end to end to a support structure. The boxes would nominally be made of metal or concrete, rectangular in shape, have openings in the front to admit sound waves and contain a sound absorptive material, such as mineral fibre or fiberglass. Another method for suppression of sound during runup is described in U.S. Pat. No. 3,386,528. The jet engines are plugged into curved tubular deflectors which direct the jet blast and sound upward into the atmosphere. Unfortunately, a considerable amount of the noise is transmitted to distant neighborhoods. The drawbacks of these methods are higher initial cost, greater labor costs, and inefficiency of sound reduction.
The improvements embodied in the present invention address and alleviate the sound propagation problems related to crowds, traffic, machinery and airplanes. The present invention presents sound absorption implements that are considerably less expensive and more effective than existing sound absorption devices.